Endor's a tough thing to explain, and just like the Space Battle I think we miss probably 80% of what is going on there just so the movie fits in a decent ammount of time.

I've always chalked up the lack of AT-AT patrols at the rear bunker to two things.

1) AT-AT's are powerful, but the large trees still tower over them and would cause a vehicle of this size and design a lot of trouble in a tight spot.

Thus the AT-ST makes a better vehicle in the still heavily wooded areas of the Imperial Base. The secondary access bunker was heavily covered with trees, yet the area around the landing platform, and presumably the area around the main generator dish/bunker were probably pretty well de-forested and were the presumed areas of attack...

2) distance...

If the AT-AT walker(s) on-planet are a large distance away, they may not reach the battle area on time... Or simply they were to stay in defense of the heavily de-forested areas around the main bunker and landing platform(s), or other garrison zones.

The AT-ST simply made a better vehicle in a tight area where maneuveability became key though... The AT-AT's maneuverable, especially for its size, but when the canopy of the trees would obscure its vision, and the trees themselves would impede the AT-AT from being effective anyway, the AT-AT(s) probably just hung back near the areas they were most effective in. IE: the cleared out zones nearer to the main areas of the Endor base.

Seeing the AT-AT on-screen in ROTJ is still one of the neater moments of that movie I think... A little reminder of those behemoths that slaughtered the rebels at Hoth.

I agree with Jesse... The ATAT probably wasn't the fighting vehicle of choice in the forests of Endor, and the one that we do spot was dropping off the prisoner (Luke) captured who knows where. Luke could have been captured far away as to divert Imperial Forces to a farther-off location. So while the ATAT and how many ATST's escorted it out to "mop up" the other rebels near the same spot Luke was "captured", the rebels were attacking the back door - out of range.

Okay, who else wants to see an extended version of the Battle of Endor with AT-ATs blowing away giant redwoods like they were toothpicks? Let's see the Ewok defend against a half dozen of those big boys, George.

(I mean, if you're gonna totally F up the OT, at least have some fun doing it.)

Blah blah blah, all explanations for those who cant deal with the fact that the Ewoks are a superior race...

The ATATs would have been easier for our furry little heroes to destroy than the ATSTs. Take out one leg, and the thing is useless. Not to mention there is no close perimeter fire power on an ATAT, so all the Ewoks had to do is swing a dead tree into one of the legs and disable it, they could then shimmy up the sides, or leap from trees and gain entry.

I've always felt that the rear bunker that was attacked was very lightly defended, and that the brunt of the "Legion" the Emperor spoke of were at the main shield generator.

You can tell just by the explosion of the generator (And the shots of how cavernous the power grid to it was) that the whole Imperial property was HUGE. We're talking literally MILES and MILES of base probably.

It's likely that the backdoor the Teddy Grahams showed to Han and company was a legitimate surprise to the Empire that the Alliance knew of it, and attacked there.

PLUS, we have a whole slew of Rebels who came with the group but who aren't present... I've also theorized that they're at the main base causing a bit of a disturbance at the same time Han and Co. attack the rear entrance.

A small backup group is called in for the backdoor attack while the main force stays at the main base protecting it from a possibly larger frontal assault because the Imperials are kind of in the dark on what's going to happen. The AT-AT's likely patrol the cleared out area up towards the main base where they're best suited, and AT-ST's handle anything away from the cleared out forest since AT-AT's would be rendered somewhat ineffective... Not really, but they're just not suited to that kind of combat.

What the Empire doesn't expect is the Teddy Grahams which throw everything into chaos basically. And one officer's stupidity opens the door for Han when he hops in the AT-ST, and voila... The mission is won, basically.

It's a bit of a mess, just like the space battle, but it's still accomplished.

We must remember, it is called a "transport". It was designed to move a mass amount of troops not a primary assault weapon. If it was it would have gun turrets all over it like a B-17 Bomber from WWII.

If it was a primary assault vehicle it would be called an "AT-ABKM" (All Terrain Armoured Butt Kicking Machine).